Mechanisms and safety assessment of support tilting for arch crossing pipelines in saline-alkali environments

Abstract

To address the 3°-4° tilting issue of an arch crossing gas pipeline support structure in a saline-alkali wetland environment, a comprehensive quality evaluation of the pipeline and welds was performed using multiple non-destructive testing (NDT) techniques, including high-precision ultrasonic thickness measurement, magneto strictive ultrasonic guided wave, radiographic testing, ultrasonic testing, and magnetic particle testing. Based on field inspection data, a three-dimensional solid finite element model of the crossing section was developed using ABAQUS to quantitatively analyze the impact of support tilting angles on pipeline stress distribution. The simulation results were validated by correlating the stress concentrations with the observed plastic deformation locations of field clamps. The research results indicate that under the current tilting condition, the maximum mises stress of the pipeline is 172 MPa, remaining within the elastic safety range of the material. Furthermore, a critical tilting threshold of 16° for early warning was determined through parametric simulations, and uneven foundation settlement as well as constraint failure due to environmental erosion were identified as the principal causal factors for the support tilting. The proposed “multi-dimensional inspection and refined modeling” evaluation method provides a scientific basis for the risk management and targeted maintenance of in-service crossing pipelines.